com.sun.tools.attach.spi.AttachProvider Maven / Gradle / Ivy
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package com.sun.tools.attach.spi;
import java.io.IOException;
import java.util.Collections;
import java.util.Iterator;
import java.util.ArrayList;
import java.util.List;
import com.sun.tools.attach.VirtualMachine;
import com.sun.tools.attach.VirtualMachineDescriptor;
import com.sun.tools.attach.AttachPermission;
import com.sun.tools.attach.AttachNotSupportedException;
import java.util.ServiceLoader;
/**
* Attach provider class for attaching to a Java virtual machine.
*
* An attach provider is a concrete subclass of this class that has a
* zero-argument constructor and implements the abstract methods specified
* below.
*
* An attach provider implementation is typically tied to a Java virtual
* machine implementation, version, or even mode of operation. That is, a specific
* provider implementation will typically only be capable of attaching to
* a specific Java virtual machine implementation or version. For example, Sun's
* JDK implementation ships with provider implementations that can only attach to
* Sun's HotSpot virtual machine. In general, if an environment
* consists of Java virtual machines of different versions and from different
* vendors then there will be an attach provider implementation for each
* family of implementations or versions.
*
* An attach provider is identified by its {@link #name name} and
* {@link #type type}. The name is typically, but not required to
* be, a name that corresponds to the VM vendor. The Sun JDK implementation,
* for example, ships with attach providers that use the name "sun". The
* type typically corresponds to the attach mechanism. For example, an
* implementation that uses the Doors inter-process communication mechanism
* might use the type "doors". The purpose of the name and type is to
* identify providers in environments where there are multiple providers
* installed.
*
* AttachProvider implementations are loaded and instantiated at the first
* invocation of the {@link #providers() providers} method. This method
* attempts to load all provider implementations that are installed on the
* platform.
*
* All of the methods in this class are safe for use by multiple
* concurrent threads.
*
* @since 1.6
*/
public abstract class AttachProvider {
private static final Object lock = new Object();
private static List providers = null;
/**
* Initializes a new instance of this class.
*
* @throws SecurityException
* If a security manager has been installed and it denies
* {@link com.sun.tools.attach.AttachPermission AttachPermission}
* ("createAttachProvider")
*/
protected AttachProvider() {
SecurityManager sm = System.getSecurityManager();
if (sm != null)
sm.checkPermission(new AttachPermission("createAttachProvider"));
}
/**
* Return this provider's name.
*
* @return The name of this provider
*/
public abstract String name();
/**
* Return this provider's type.
*
* @return The type of this provider
*/
public abstract String type();
/**
* Attaches to a Java virtual machine.
*
* A Java virtual machine is identified by an abstract identifier. The
* nature of this identifier is platform dependent but in many cases it will be the
* string representation of the process identifier (or pid).
*
* This method parses the identifier and maps the identifier to a Java
* virtual machine (in an implementation dependent manner). If the identifier
* cannot be parsed by the provider then an {@link
* com.sun.tools.attach.AttachNotSupportedException AttachNotSupportedException}
* is thrown. Once parsed this method attempts to attach to the Java virtual machine.
* If the provider detects that the identifier corresponds to a Java virtual machine
* that does not exist, or it corresponds to a Java virtual machine that does not support
* the attach mechanism implemented by this provider, or it detects that the
* Java virtual machine is a version to which this provider cannot attach, then
* an AttachNotSupportedException is thrown.
*
* @param id
* The abstract identifier that identifies the Java virtual machine.
*
* @return VirtualMachine representing the target virtual machine.
*
* @throws SecurityException
* If a security manager has been installed and it denies
* {@link com.sun.tools.attach.AttachPermission AttachPermission}
* ("attachVirtualMachine"), or other permission
* required by the implementation.
*
* @throws AttachNotSupportedException
* If the identifier cannot be parsed, or it corresponds to
* to a Java virtual machine that does not exist, or it
* corresponds to a Java virtual machine which this
* provider cannot attach.
*
* @throws IOException
* If some other I/O error occurs
*
* @throws NullPointerException
* If id is null
*/
public abstract VirtualMachine attachVirtualMachine(String id)
throws AttachNotSupportedException, IOException;
/**
* Attaches to a Java virtual machine.
*
* A Java virtual machine can be described using a {@link
* com.sun.tools.attach.VirtualMachineDescriptor VirtualMachineDescriptor}.
* This method invokes the descriptor's {@link
* com.sun.tools.attach.VirtualMachineDescriptor#provider() provider()} method
* to check that it is equal to this provider. It then attempts to attach to the
* Java virtual machine.
*
* @param vmd
* The virtual machine descriptor
*
* @return VirtualMachine representing the target virtual machine.
*
* @throws SecurityException
* If a security manager has been installed and it denies
* {@link com.sun.tools.attach.AttachPermission AttachPermission}
* ("attachVirtualMachine"), or other permission
* required by the implementation.
*
* @throws AttachNotSupportedException
* If the descriptor's {@link
* com.sun.tools.attach.VirtualMachineDescriptor#provider() provider()} method
* returns a provider that is not this provider, or it does not correspond
* to a Java virtual machine to which this provider can attach.
*
* @throws IOException
* If some other I/O error occurs
*
* @throws NullPointerException
* If vmd is null
*/
public VirtualMachine attachVirtualMachine(VirtualMachineDescriptor vmd)
throws AttachNotSupportedException, IOException
{
if (vmd.provider() != this) {
throw new AttachNotSupportedException("provider mismatch");
}
return attachVirtualMachine(vmd.id());
}
/**
* Lists the Java virtual machines known to this provider.
*
*
This method returns a list of {@link
* com.sun.tools.attach.VirtualMachineDescriptor} elements. Each
* VirtualMachineDescriptor describes a Java virtual machine
* to which this provider can potentially attach. There isn't any
* guarantee that invoking {@link #attachVirtualMachine(VirtualMachineDescriptor)
* attachVirtualMachine} on each descriptor in the list will succeed.
*
* @return The list of virtual machine descriptors which describe the
* Java virtual machines known to this provider (may be empty).
*/
public abstract List listVirtualMachines();
/**
* Returns a list of the installed attach providers.
*
* An AttachProvider is installed on the platform if:
*
*
* It is installed in a JAR file that is visible to the defining
* class loader of the AttachProvider type (usually, but not required
* to be, the {@link java.lang.ClassLoader#getSystemClassLoader system
* class loader}).
The JAR file contains a provider configuration named
* com.sun.tools.attach.spi.AttachProvider in the resource directory
* META-INF/services.
The provider configuration file lists the full-qualified class
* name of the AttachProvider implementation.
*
* The format of the provider configuration file is one fully-qualified
* class name per line. Space and tab characters surrounding each class name,
* as well as blank lines are ignored. The comment character is
* '#' (0x23), and on each line all characters following
* the first comment character are ignored. The file must be encoded in
* UTF-8.
*
* AttachProvider implementations are loaded and instantiated
* (using the zero-arg constructor) at the first invocation of this method.
* The list returned by the first invocation of this method is the list
* of providers. Subsequent invocations of this method return a list of the same
* providers. The list is unmodifable.
*
* @return A list of the installed attach providers.
*/
public static List providers() {
synchronized (lock) {
if (providers == null) {
providers = new ArrayList();
ServiceLoader providerLoader =
ServiceLoader.load(AttachProvider.class,
AttachProvider.class.getClassLoader());
Iterator i = providerLoader.iterator();
while (i.hasNext()) {
try {
providers.add(i.next());
} catch (Throwable t) {
if (t instanceof ThreadDeath) {
ThreadDeath td = (ThreadDeath)t;
throw td;
}
// Ignore errors and exceptions
System.err.println(t);
}
}
}
return Collections.unmodifiableList(providers);
}
}
}